Optical fiber twisted pair standard
fiber optic line
The full name of the optical fiber is called optical fiber, the English name is OPTIC FIBER, and some are called OPTICAL FIBER. The characteristics of optical fiber are: fast transmission speed, long distance, large content, and no electromagnetic interference, not afraid of lightning strikes, difficult to eavesdrop on the outside, non-conductive, no grounding trouble between devices, etc.
In high-end server/workstation hard disks, Fibre Channel is also used as the SCSI hard disk interface. Fibre Channel is a high-performance connectivity standard for bidirectional, serial data communication between servers, mass storage subnets, and peripherals via hubs, switches, and point-to-point connections. Fibre Channel provides long-range connectivity and high-speed bandwidth for the need to efficiently transfer large amounts of data between servers and storage media. It is an ideal technology for storage area networks, cluster computers and other data-intensive computing facilities. Its interface transfer speed is divided into 1GB and 2GB and so on.
Twisted Pair Cabling Standards
Twisted pair (Twisted Pairwire, TP) is the most commonly used transmission medium in integrated wiring engineering. The twisted pair is made up of two 22-26 gauge insulated copper wires intertwined with each other. Twisting two insulated copper wires together at a certain density can reduce the degree of signal interference, and the radio waves radiated by each wire during transmission will also be canceled by the radio waves emitted by the other wire. If one or more pairs of twisted pairs are placed in an insulating sleeve, it becomes a twisted pair cable. For example, the five, six, and seven twisted pairs commonly used in local area networks are composed of four twisted pairs. of. In a twisted pair, different pairs have different twist lengths. Generally speaking, the twist length is within 13 mm, twist in the counterclockwise direction, and the twist length of adjacent pairs is more than 12.7 cm.
Although twisted pair is limited in transmission distance, channel width and data transmission speed compared with other transmission media, the price is relatively low, and its bad restrictions have little effect in general Fast Ethernet, so at present Twisted pair remains the preferred transmission medium in corporate LANs.
The twisted pair can be divided into two types: Unshielded Twisted Pair (UTP) and Shielded Twisted Pair (STP). The shielded twisted pair is obviously better than the unshielded twisted pair in wire diameter, and because it has better shielding performance, it also has better electrical performance. However, since the price of shielded twisted pair is more expensive than that of unshielded twisted pair, and the performance of unshielded twisted pair has little effect on ordinary enterprise LANs, it is even difficult to detect them. Usually unshielded twisted pair. However, except for Category 7 twisted pair, because it needs to achieve full-duplex 10 Gbps rate transmission, only shielded twisted pair can be used, and there is no unshielded Category 7 twisted pair. Category 6 twisted pair is also generally recommended to use shielded twisted pair.
With the development of network technology and the improvement of application requirements, the transmission medium standard of twisted pair has also been developed and improved step by step. From the first category 1 and 2 lines to the highest category 7 lines today, it is reported that there is still room for further development of this medium standard. In these different standards, their transmission bandwidth and rate have also been improved accordingly. Category 7 lines have reached 600 MHz, or even 1.2 GHz bandwidth and 10 Gbps transmission rate, supporting the transmission of Gigabit Ethernet.
These different types of twisted pairs are marked in this way. If they are standard types, they are marked in CATx mode. For example, the commonly used Category 5 and Category 6 cables are marked as CAT 5 and CAT 6 on the outer skin of the line. And if it is an improved version, it should be marked in the xe way. For example, the super five-category line will be marked as 5e (the letters are lowercase, not uppercase). In North America, the three most influential cabling organizations in the world are as follows.
ANSI (American National Standards Institute, American National Standards Institute)
TIA (Telecommunication Industry Association)
EIA (Electronic Industries Alliance)
Since TIA and ISO often coordinate in the formulation of standards, the differences between the standards promulgated by TIA and ISO are not very large. At present, in North America and even the world, the most widely used twisted pair standards are ANSI/EIA/TIA-568A and ANSI/EIA/TIA-568B (actually it should be ANSI/EIA/TIA-568B.1, referred to as ANSI/EIA/TIA-568B.1). for T568B). The main difference between the two standards is the difference in the core wire sequence.
twisted pair standard
CAT-1: Currently not recognized by TIA/EIA. Lines previously used in legacy telephone networks (POTS), ISDN and doorbells.
CAT-2: Currently not recognized by TIA/EIA. In the past, it was commonly used in 4 Mbit/s Token Ring networks.
CAT-3: Currently defined and recognized by TIA/EIA-568-B. And provide 16MHz bandwidth. Used to be commonly used in 10Mbps Ethernet networks.
CAT-4: Currently not recognized by TIA/EIA. Provides a bandwidth of 20MHz. In the past, it was commonly used in 16 Mbit/s Token Ring networks.
CAT-5: Currently defined and recognized by TIA/EIA-568-A. And provide 100MHz bandwidth. Currently commonly used in Fast Ethernet (100 Mbit/s).
CAT-5e: Currently defined and recognized by TIA/EIA-568-B. And provide 100MHz bandwidth. Currently, it is commonly used in Fast Ethernet and Gigabit Ethernet (1Gbit/s).
CAT-6: Currently defined and recognized by TIA/EIA-568-B. Provides a bandwidth of 250MHz, which is one and a half times higher than CAT-5 and CAT-5e.
CAT-6A: Future use in 10 Gigabit Ethernet (10 Gbit/s).
CAT-7: An informal name applied to ISO/IEC 11801 Class F cabling. This standard specifies four individually-shielded pairs (STP) inside an overall shield. Designed for transmission at frequencies up to 600 MHz.